1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method capable of executing reduction processing for reducing an amount of recording material used for formation of non-edge portions of an image.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2007-176158 discusses a method for reducing usage amount of recording material (number of recording dots), while keeping image quality, in order to achieve a good balance between high image quality and low running cost. The technique discussed in Japanese Patent Application Laid-Open No. 2007-176158 reduces usage amount of recording material (number of recording dots) by thinning data of non-edge portions of images according to a predetermined thinning ratio, while maintaining image quality, and thus realizes cut-down of running cost.
However, in the technique discussed in Japanese Patent Application Laid-Open No. 2007-176158, the thinning ratio of the non-edge portions is constant without depending on colors (e.g., difference between black character/color character) of the images. For this reason, a difference in color density in the non-edge portions becomes noticeable, between when the images are made up of color and when made up of black, and thus image quality may be degraded in some cases.
Further, Japanese Patent Application Laid-Open No. 2007-176158 is described on the precondition that binary data is input, as a detection processing of the edge portions and the non-edge portions. If black 100% or the like is input, it is often the case that binary data also becomes a 100% duty image. On the other hand, if grey or color image or the like is input, it is more often the case that it becomes an image of non-100% duty. In the binary data in which an image of non-100% duty has been binarized, it is more often the case that pixels which do not record dots exist also inside characters. Therefore, if detection processing of the edge portions and the non-edge portions is performed using the binary data of non-100% duty as input, edges will eventually exist also inside the characters.
Further, edge processing performed using multivalued data as input is also known. In this case, although edges do not exist inside the characters, processing load thereof becomes larger than that of detection processing of binary edge portions and non-edge portions. If the edge processing is realized by hardware, there is a possibility that circuit scale will eventually become larger, and thus product cost will eventually become high. There is a possibility that a personal computer (PC) requires a high-spec performance, if the edge processing is realized as a program (on software basis) on a recording apparatus or the like, or processing time will eventually become long.